Malignant tumors are often complicated with venous thrombosis and pulmonary embolism (PE), particularly in lung cancer. However, owing to the limited data regarding the clinical course about PE in lung cancer patients, the aim of this study is to analyze the risk factors and prognosis of patients with PE and lung cancer. We performed a retrospective case–control study, the clinical data of 90 patients in the First Affiliated Hospital of People's Liberation Army General Hospital between Jan 2010 and Jan 2015 were analyzed, including 30 lung cancer patients with PE (PE group), 60 lung cancer patients without PE (non-PE group), treated during the same period. Logistic regression analysis was applied to explore risk factors of PE. Patient survival was also compared with matched controls via a log-rank test. The multivariate analysis revealed that adenocarcinoma, stage III to IV, high D-dimer, and low PaO2 were independent risk factors. The survival time in patients with PE was remarkably lower than that in patients without PE (P < .0005). Adenocarcinoma, stage III to IV, high D-dimer and low PaO2 are important risk factors for lung cancer patients with PE. PE suggested a poor prognosis in lung cancer patients.